For the next three weeks, we’ll be reading heavy-duty, seminal sections of the Torah: The Exodus, the splitting of the sea, and the giving of the Ten Commandments.

For the 8th plague, locusts polish off everything in Egyptian fields that hadn’t been destroyed by the hail. The plague of locusts needs no “gee, how did that happen?” head-scratching. Locust plagues plague us to this day. Even the collective noun for locusts is plague, i.e., “a plague of locusts,” like “a gaggle of geese.” If you watch the 1937 film The Good Earth, you’ll see an authentic-looking swarm. It looks authentic because it is. The special effects people hadn’t figured out how to make a good fake locust plague when they heard a real one was happening elsewhere, and they were able to rush a camera crew there to film it.

The ninth plague, darkness, is one I’ve often written about in depth here. Speculations as to its natural origin (a khamsin? Solar eclipse?) are irrelevant. This not an ordinary lack of light. As I wrote last year, “No, this is an almost palpable darkness, darker than night (Rashi). Lamps and candles are useless (Nachmanides). It’s like the darkness of the chaos preceding creation; or maybe it’s a taste of hell (Midrash, Exodus Rabbah). The Egyptians do not leave their homes. They are paralyzed, isolated, demoralized. This is national clinical depression.” And the Israelites have light in Goshen.

Pharaoh is now willing (for the moment, anyway) to let the Israelites leave, as long as they leave their flocks. No deal, so the 10th plague follows, the slaying of the Egyptian firstborn. In the ensuing chaos, the Israelites flee.

Before the 10th plague, the Israelites are given instructions on how to celebrate the first Passover. Each household is to sacrifice an unblemished one-year old male lamb, “take from the blood and place it upon the doorposts and the lintels of the homes in which they shall eat it. They shall eat the flesh on this night, roasted over fire and accompanied by matzot and bitter herbs… roasted over fire whole…Thus shall you eat it: with your loins girded, your shoes upon your feet and your staff in your hands.” (12:3-11) Then the Lord will slay all the firstborn of Egypt, human and animal, but pass over the Israelite houses that have been marked with blood.

But why do they need to mark their entries with blood? This and the requirement to be dressed ready to go are the only actions that are commanded only for that first Passover. Surely the Lord doesn’t need this mark to figure out who’s who. Rabbi Michael Hattin, in his d’var “The ‘Blood Service’ of the Paschal Sacrifice.” posits that this is a birth motif:

“Israel is safe and secure within, while without, chaos and confusion reign. As dawn breaks, the screams subside, the bolted doors are flung open, and the people of Israel step into the blinding light of freedom. The symbolism of the experience is crystal clear: on that night of terror, a nation is being born, and on the morrow they are brought forth. The threshold, consisting of doorposts and lintel stained with blood, defines the decisive moment in time and space that separates the protection and stillness of the ‘womb’ from the harsh cries of daylight. To cross that verge, to pass through that painful portal, is to experience that most excruciating and exhilarating of all experiences: birth.”

(Personally, I didn’t find it exhilarating at the time.) Since birth only occurs once, the marking with blood is not repeated. R’ Hattin finds parallels for the symbolism of blood and birth in Ezekiel 16:1-7 [“As for your birth, …you were instead cast out into the field in your repulsive state…. I passed upon you “and saw you wallowing in your blood, and I called to you: ‘by your blood you shall live, by your blood you shall live!'”] and in Midrash Mekhilta, Parashat Bo Chapter 5, where the blood of the paschal lamb and the blood of circumcision are presented as means by which the Israelites earn redemption.

Immediately after leaving Egypt, the Israelites are given a few more laws, concerning the perpetual observance of Passover, the dedication of the firstborn, and tefillin (13:16, “a sign upon your hand and frontlets between your eyes”). These are all actions to help the Israelites remember and teach their children what happened.

Next time: The Israelites learn that Pharaoh has changed his mind yet again, and wants them back.

But how many locusts does it take to make a swarm? It sounds like the start of a bad joke, but understanding and controlling locust plagues is something we’ve been striving to do for thousands of years. If we can understand what makes a swarm, hopefully we can understand how to stop it. This is exactly what our international research team tried to do – and the results are in. The answer is just three.

Cannibal creatures

Our study, published in Physical Review E, used mathematical modelling to show that a locust in a swarm must be able to interact with at least two neighbours simultaneously. Without those two neighbours, the insects can’t reproduce the striking spontaneous changes in direction we are used to seeing in flocks of starlings, schools of fish – and swarms of locusts.

By watching locusts move around a ring, we identified some interesting behaviour. Small numbers of locusts move around the ring at random, but larger groups start to march together in the same direction. These groups will then spontaneously switch to march in the other direction. The more locusts in a group the longer the time interval between switches and the more stable the swarm.

We were able to reproduce this behaviour in a mathematical model and discovered that locusts move more randomly when they don’t have near neighbours. So, forming a swarm is all about neighbours – but that doesn’t make it “neighbourly”. The reason locusts pay so much attention to their neighbours is because locusts are cannibals.

The best way for swarming insects to get the protein and salt they need is to eat each other. And that’s bad news for any locust that isn’t watching what its neighbours are up to.

Consequently, when in a group, any locust that is out of line with its neighbours will expose its vulnerable flank and face a greater chance of being cannibalised. By being in line, they will be safer – but will also help hold the swarm together.

Q: What do you call someone who derives pleasure from the bread of affliction? A: A matzochist.

A blind man is sitting on a park bench. A Rabbi sits down next to him. The Rabbi is chomping on a piece of matzoh. Taking pity on the blind man, he breaks off a piece and gives it to the blind man. Several minutes later, the blind man turns, taps the Rabbi on the shoulder and asks, “Who wrote this #&*$ ?!!” (BTW, I first heard that one from Cantor Norman Swerling, z’l. IGP)

A 14-year-old boy who complained of a chronic rash on his left arm and hand has been diagnosed with a “tefillin rash” – caused by the chemical potassium dichromate, which is used to process the black straps of the phylacteries.

An article in the September issue of the Hebrew-language medical journal Harefuah (of the Israel Medical Association) by doctors at Sha’are Zedek Medical Center describes the unusual case.

The boy was described as the youngest person to be recorded with such an allergic reaction to leather tefillin straps. Other victims have been as old as 77 (such a man was diagnosed after 20 years of suffering from allergic contact dermatitis). Others were devout men, including rabbis, who wear their phylacteries not only to recite the morning prayers but also keep them on all day as an “extra mitzva.”

“Tefillin allergy” is relatively rare in Israel. It is due not to the tefillin themselves, but to the chemicals used to process the leather straps. The rash appeared in the boy about a year after he first began to don phylacteries for his bar mitzva, wrote Drs. Pinhas Hashkes and Efraim Sagi of the Jerusalem hospital.

According to estimates, about a quarter of the male Jewish population in Israel wears tefillin on a regular basis. But as they are worn for less than an hour at a time, the allergic response does not appear in all users with sensitivity to the chemical. Some who were diagnosed turned to their rabbis for permission to wear their phylacteries over their sleeves instead of their bare arm, while others place clear cling plastic under the leather straps. In addition, a Bnei Brak shop called Machon Pe’er sells tefillin processed without the offending chemical.